1. Field of the Invention
This invention relates to a configurable switch having a configurable base and a configurable plunger, which together permit the adjustable arrangement of contacts into one of several switch configurations.
2. Description of Related Art
Industrial limit switches, such as global limit switches, safety interlocks, safety solenoid interlocks and cable pull limit switches, are used in a wide variety of industrial applications. Limit switches contain switches that are manufactured to suit the particular application.
Typically, switches used in these products are designed and manufactured for a particular contact arrangement. Such switches generally contain two or more circuits having one or more normally closed (NC) contacts and/or one or more normally open (NO) contacts. Conventional arrangements typically include one normally open/one normally closed, also called a "single pole" arrangement, or two normally open/two normally closed, also called a "double pole" arrangement. In recent years, two normally closed and three normally closed/one normally open contact arrangements have been developed. Traditionally, a separate switch design is required for each contact arrangement. Separate switch designs often require unique parts that are not interchangeable among separate designs. Therefore, four separate common switch designs typically require four sets of unique components.
Conventional industrial limit switches often require additional normally closed contacts for added redundancy. Limit switch applications often require at least three positively driven, normally closed contacts along with one normally open monitor circuit.
Conventional switch mechanisms used in typical industrial limit switches are: one normally open/one normally closed; two normally open/two normally closed and two normally closed contact arrangements. Typically, the only common component among the three most common switch mechanism contact arrangements is a terminal screw. Therefore, according to one manufacturer, approximately twenty-seven separate components are currently required to produce three different switches.
Olsen, U.S. Pat. No. 5,569,890, is an example of a double pole switch which has a typical housing and plunger arrangement. It would not be possible to construct a switch having an arrangement of four normally closed contacts from the same components used in the double pole arrangement taught by the Olsen patent.
In the drawings of the present application, FIG. 1 shows an assembled prior art switch 5, having two circuits, such as used in typical industrial limit switches. Switch 5 is arranged in a one normally open/one normally closed circuit configuration. Switch 5 has a single normally open circuit, shown near the bottom of FIG. 1. FIG. 1 shows switch 5 in a normal position, i.e., when switch 5 is at rest. In the normal position in the normally open circuit, there is no electrical contact between moveable contact 45' and stationary contact 30'. The normally closed circuit, shown near the top of FIG. 1, occurs in the normal position when a pair of moveable contacts 45' electrically contact a corresponding pair of stationary contacts 30'. When plunger 40' is depressed, the normally open circuit closes and the normally closed circuit opens. Switch 5 taught in FIG. 1 is not configurable into any other circuit configuration other than by removing or disconnecting one of the two circuits.
FIG. 2 shows a disassembled prior art two-circuit switch 6 used in typical industrial limit switches. Switch 6 shown in FIG. 2 is assembled to create a two normally closed circuit configuration. As shown, switch 6 includes: base 15', plunger 40', moveable contacts 45', return spring 55, stationary contacts 30' and 30", terminal screws 70' and cover 75'. Stationary contacts 30' and 30" slidably mount within bosses 17 molded within base 15'. In the normal position, both moveable contacts 45' electrically contact stationary contacts 30' to create two normally closed circuits within switch 6. Like switch 5 shown in FIG. 1, switch 6 shown in FIG. 2 is not configurable into any other circuit configuration other than by removing or disconnecting one of the two circuits.
FIG. 3 shows a disassembled, four-circuit, prior art switch 7 used in typical industrial limit switches. Switch 7 is assembled to create a two normally open/two normally closed circuit configuration. As shown, switch 7 includes base 15', plunger 40', plunger attachment 41, moveable contacts 45', return spring 55, stationary contacts 30', terminal screws 70', terminal nuts 71, spacers 60 and cover 75'. Stationary contacts 30' slidably mount within bosses 17 molded within base 15'. In the normal position, two moveable contacts 45' electrically contact two stationary contacts 30' to create two normally closed circuits within switch 7 and the two moveable contacts 45' are electrically spaced from stationary contacts 30' to create two normally open circuits within switch 7. Two styles of stationary contacts 30' and 30" are also required in switch 7. Like switch 5 shown in FIG. 1 and switch 6 shown in FIG. 2, switch 7 shown in FIG. 3 is not configurable into any other circuit configuration other than by removing or disconnecting one or more of the four circuits.
Other than terminal screws 70', the components used in prior art switches 5, 6, 7 are typically not interchangeable. Therefore, to assemble three separate conventional switches 5, 6, 7, each having different circuit configurations, requires at least twenty-seven unique components.